Story Highlights

Water Quality. Seasonal high flows into floodplains and wetlands improve water quality by allowing these areas to filter sediment and pollutants from our rivers and lakes.

Flood Protection. Coordinating dam operations with the strategic use of the most flood-prone areas can reduce flood risk for communities. Floods cause $30–50 billion worth of damage in the U.S. every decade.

Wildlife & Recreation. Natural flow patterns trigger fish spawning and migration. They also sustain scenic natural lands and give life to floodplains and wetlands, which are among the most productive areas for fish and other wildlife. Rivers and lands that benefit from natural flows support commercial and recreational fishing and other outdoor-related recreation that generate billions of dollars each year.

A bi-partisan survey found that 78% of American voters are seriously concerned about the health of our nation’s rivers and lakes.*

Habitat and flow restoration work on Caddo Lake and Big Cypress Bayou in Texas have allowed the return of paddlefish. Read More.

Paddlefish Restoration: Learn how restoring natural flows has allowed the return of an ancient fish to Texas's Caddo Lake.

An Opportunity for Change

For much of the 20th century, the United States built thousands of large dams and other water projects to meet the nation’s growing need for water, food, flood protection, hydropower and navigation. But since their construction 40-80 years ago, the operations of very few public dams have been fully reviewed and updated to meet current needs and to prepare for future circumstances. We now have the opportunity to modernize the operation of these water projects to improve the social, economic and environmental benefits they provide now and for generations to come.

Higher Returns on Investments

Today, engineers better understand that operating dams as part of whole-river systems increases the benefits they provide, and managing dams in coordination with downstream flood-prone lands enables us to more efficiently meet diverse social needs. For example, while flood protection is maximized by keeping reservoirs empty, doing so minimizes their ability to provide water supplies, hydropower and recreation. Using the natural floodplain features downstream of dams to store infrequent floodwaters enables us to keep more water in reservoirs and increase the regular and consistent economic benefits from these other uses.

In 2011, this approach was studied by the U.S. Army Corps of Engineers, The Nature Conservancy and University of California-Davis in two river basins — Georgia’s and South Carolina’s Savannah and California’s Mokelumne. The Savannah River study found that small changes in floodplain management enable the use of up to 50% of the existing flood storage capacity for hydropower and recreation, producing a net benefit of more than $12 million per year, without increasing flood risk and with additional benefits for water supply and the environment. The Mokelumne River study found similarly modest shifts in floodplain management frees up 25% to 50% of flood storage for public water supply—enough additional water for nearly 450,000 people — while maintaining flood protection and increasing hydropower generation and improving habitat for declining salmon.

In another example along Arizona's Bill Williams River, changes in dam flows in an arid region have helped bring a dying forest back to life. Watch a video about this work.

Demonstrating Success – The Sustainable Rivers Project

The advantages of making systematic changes in dam operations to more efficiently achieve multiple benefits have been demonstrated through more than a decade of national collaboration between the Corps, the Conservancy, and other partners under the Sustainable Rivers Project (SRP).

* A national survey of registered voters conducted in 2009 by Democratic polling firm Fairbank, Maslin, & Associates (FMM&A) and Republican polling firm Public Opinion Strategies (POS) to gauge support for increased investments in the protection of land, water, and wildlife.

The Nature Conservancy is a nonprofit, tax-exempt charitable organization (tax identification number 53-0242652) under Section 501(c)(3) of the Internal Revenue Code. Donations are tax-deductible as allowed by law.